abstract class GirlFriend {
	abstract void speak();
	abstract void cooking();
	}
class ChinaGirlFriend extends GirlFriend {
	void speak () {
	System.out.println("你好");
	}
	void cooking() {
	System.out.println("水煮鱼");
	}
}
class AmericanGirlFriend extends GirlFriend {
	void speak() {
	System.out.println("hello");
	}
	void cooking (){
	System.out.println("beef");
	}
}
class Boy {
GirlFriend friend;
	void setGirlfriend(GirlFriend f) {
	friend=f;
}
void showGirlFriend () {
	friend.speak();
	friend.cooking();
	}
}
public class p130 {
public static void main(String args[]) {
	GirlFriend girl =new ChinaGirlFriend();
	Boy boy=new Boy();
	boy.setGirlfriend(girl);
	boy.showGirlFriend();
	girl=new AmericanGirlFriend();
	boy.setGirlfriend(girl);
	boy.showGirlFriend();
	}
}
